Rewrite the content – you can rewrite your blog post and then publish it on these sites so that the content isn't duplicate. Talk to the site owner – there is no harm in asking the site owner or editor to add a rel=canonical
Post by Email
Post by Email is a way of publishing posts on your blog by email. Any email client can be used to send the email, allowing you to publish quickly and easily from devices such as cell phones. Please note you can only publish to one blog using one e-mail message at a time. (Wordpres Doc)
For the above solution you must send the post in another email of another WP site.
